TR10: Traveling-Wave Reactor

Wave of the future: Unlike today’s reactors, a traveling-wave reactor requires very little enriched uranium, reducing the risk of weapons proliferation. (Click here for a larger diagram, also on page 3). The reactor uses depleted-uranium fuel packed inside hundreds of hexagonal pillars (shown in black and green). In a “wave” that moves through the core at only a centimeter per year, this fuel is transformed (or bred) into plutonium, which then undergoes fission. The reaction requires a small amount of enriched uranium (not shown) to get started and could run for decades without refueling. The reactor uses liquid sodium as a coolant; core temperatures are extremely hot--about 550 ºC, versus the 330 ºC typical of conventional reactors.
Bryan Christie Design

Enriching the uranium for reactor fuel and opening the reactor periodically to refuel it are among the most cumbersome and expensive steps in running a nuclear plant. And after spent fuel is removed from the reactor, reprocessing it to recover usable materials has the same drawbacks, plus two more: the risks of nuclear-weapons proliferation and environmental pollution.

These problems are mostly accepted as a given, but not by a group of researcher­s at Intellectual Ventures, an invention and investment company in Bellevue, WA. The scientists there have come up with a preliminary design for a reactor that requires only a small amount of enriched fuel--that is, the kind whose atoms can easily be split in a chain reaction. It's called a traveling­-wave reactor. And while government researchers intermittently bring out new reactor designs, the traveling-wave reactor is noteworthy for having come from something that barely exists in the nuclear industry: a privately funded research company.

As it runs, the core in a traveling-­wave reactor gradually converts nonfissile material into the fuel it needs. Nuclear reactors based on such designs "theoretically could run for a couple of hundred years" without refueling, says John G­illeland, manager of nuclear programs at Intellectual Ventures.

Gilleland's aim is to run a nuclear reactor on what is now waste. ­Conventional reactors use uranium-235, which splits easily to carry on a chain reaction but is scarce and expensive; it must be separated from the more common, nonfissile uranium-238 in special enrichment plants. Every 18 to 24 months, the reactor must be opened, hundreds of fuel bundles removed, hundreds added, and the remainder reshuffled to supply all the fissile uranium needed for the next run. This raises proliferation concerns, since an enrichment plant designed to make low-enriched uranium for a power reactor differs trivially from one that makes highly enriched material for a bomb.

But the traveling-wave reactor needs only a thin layer of enriched U-235. Most of the core is U-238, millions of pounds of which are stockpiled around the world as leftovers from natural uranium after the U-235 has been scavenged. The design provides "the simplest possible fuel cycle," says Charles W. Forsberg, executive director of the Nuclear Fuel Cycle Project at MIT, "and it requires only one uranium enrichment plant per planet."

The fuel in this reactor is Pu-239. The energy content in 1 lb of Pu-239 is equivalent to more than 2,000,000 lbs of coal, so nuclear power produces an enormous amount of energy and an extremely small amount of waste.

Currently we have 104 nuclear reactors in operation in the US, which generate about 20% of our electricity. The total amount of spent fuel discharged is about 2,000 tons per year. Of this, 95% is U-238 (which could be used as fuel in the Wave reactor), 4% is fission products (waste), 1% is transuranics (TRU). Of the 1% TRU, 90% is Pu, which can be recycled as fuel. The remaining 10% (0.1% of the total) is Np, Am, and Cm, which is considered waste, but can be recycled in a fast reactor like the Wave. The amount of fission products (waste) generated each year is 4% of 2,000 tons or 160,000 lbs. There are 300 million people in the US, so the average share of the nuclear waste is 160,000 lbs / 300 million = 0.0005 lbs, or 0.2 grams per person per year. If you received 100% of your electricity from nuclear power for your entire lifetime, all of the nuclear waste generated from your use would fit in a coffee cup. Compare this to the average person's carbon footprint of 20 tons of CO2 per year.

How radioactive will it be?

The radioactivity of the end products from the Wave reactor would be essentially the same as from the current generation of reactors.

What is its effective half-life?

The half-lives of the numerous fission products vary from a fraction of a second to many years. It takes about 500 years for the fission products to decay to same level of radioactivity as the natural uranium we started with.

How much shielding will it require?

Spent fuel is stored under water for at least 5 years to allow the fuel to cool (water is also an excellent shielding material). After that the fuel can be transferred to dry storage casks, which use steel and concrete for shielding. Six inches of concrete will stop more than 90% of the radiation from the spent fuel. A typical cask has about 3 inches of steel (for gamma shielding) and almost 3 feet of heavily reinforced concrete (for both gamma and neutron shielding).

What is its potential for mischief?

None. The combination of physical security, the huge mass of the storage systems, and self-protecting nature of radioactive materials make spent fuel extremely unattractive for mischief or misuse.

2186 Days Ago

03/08/2009

Does this all sound too good to be true?

The only by-product is a small fraction of what we get now? And it's fail-safe?

What shuts this down is my question. I know we drop neutron absorbers into current reactors, and they end the chain reaction, and the reactor doesn't over-heat and destroy itself. How do we accomplish stopping the chain reaction here?

My impression -- and I'm pretty much Joe Average Citizen here -- is that once this thing is lit, you're not going to put it out. And following that train of thought, if you can't put it out, and the cooling system hiccups, does it want to melt itself down?

Do I have that right?

2186 Days Ago

03/08/2009

The Wave reactor, like other reactors, would have a control system to shutdown the reactor. It would have to be shutdown for periodic inspections and maintenance (usually required once a year or once every two years). The control system could be control rods or a moveable neutron reflector (the reflector would surround the core and is necessary to maintain criticality. Move the reflector and neutrons escape, shutting down the reaction).

Read about the Toshiba 4S reactor for more info on reflectors. The 4S has some similarities to the Wave, but the fuel is enriched U, not depleted, and the core is vertical, not horizontal. Both burn slowly from end to end. The design life of the 4S core is 30 years.

From Wikipedia:

"The 4S is a fast neutron reactor. It uses neutron reflector panels around the perimeter to maintain neutron density. These reflector panels replace complicated control rods, yet keep the ability to shut down the nuclear reaction in case of an emergency."

Also, although it may be theoretically possible to design a core that lasts 100 years, the first generation of Wave reactors would have cores with shorter lifetimes, say 5 or 10 years. Then the reactor vessel will be smaller, and more importantly, spent fuel can be replaced with new, improved fuel designs at each refueling.

2185 Days Ago

03/09/2009

Even if if only takes 500 years for the waste products to decay to nominal levels of radioactivity, that's over twice the length of time that the US has been in existence, and almost five times as long as we have even known about radioactivity.

Would it not be a good idea to encase the cooled-down dry wastes and bury them in a deep ocean subduction zone, where they can be "recycled" into the mantle over the longer view, with no human management required or even practical (except via robot sentries) at this point in our technological development?

2185 Days Ago

03/09/2009

There are a number of possible disposal options, including deep seabed. Above ground was selected because it is accessible. Today's waste may be the fuel of the future.

1181 Days Ago

12/08/2011

There are several things that you need to understand.

*First*, most isotopes are unstable, that is, they decay into something that is then stable. This is true for everything heavier than Hydrogen. There are stable forms of all elements lighter than lead, but more unstable forms than stable forms.

For most trans-uranics, this means that they will someday be non radioactive lead. That time may be ten Billion years, or it may be a couple of milliseconds, or anything in between. It's different for every isotope.

*Second*, we are all surrounded by radiation, and always have been. We get this stuff in the first place by concentrating it.

*Third*, the more radioactive a substance is, the faster it decays. The very high level radioactive elements don't stick around very long. That's why they are so radioactive.

*Fourth*, the fission process works because certain atoms, like Uranium or Plutonium absorb stray neutrons, and then split in two (approximately) releasing two 'daughter' products like cesium or strontium, and some neutrons. But, the energy of the neutrons (Think temperature) determines how likely the neutron is to cause a fission event.

This neutron energy is in turn controlled by the temperature of the core and the moderator (Usually graphite). The moderator temperature is critical, as there is only a narrow band of neutron energies that can be absorbed by the fuel and cause fission. Too hot, the reaction shuts down. Too cold, the reaction shuts down.

At other temperatures, the neutron either bounces off, or is absorbed, changing the isotope of that atom. Unless the isotope is very unstable, this will just reduce the rate of fission.

Unfortunately, the top end of the temperature band is higher than the melting point of steel. Not however higher than the melting point of graphite. It is though, quite far above the flash point of graphite, the temperature at which graphite burns.

For this type of reactor to work, you first have to shape the fuel load. Then, you bring the vessel up to something above the minimum fission temperature and you wait.

As the mixture ripens, you need to give it less and less heat to keep it above the minimum temperature. Finally, you can capture the heat.

At steady state, most of the heat is being used to make electricity. Of course, you want to insulate the reactor area, so that most of the heat escaping can be used for generation.

Standing Wave is really just a marketing term. This is really a slow breeder reactor. They have been studied for decades, but seldom used for power production.

This post is getting too long, but one last point.

*Fifth*, most of the 'waste' from a nuclear reactor is unused fuel. The fuel may be 'spent', meaning that the readily fissile material is used up, but there remains other unused fuel in it (that would be the Plutonium)as well as breeding stock (that would be the 'depleted' uranium). These two materials are the majority of the 'waste'.

If the reaction temperature is changed, then the reactor can run on the plutonium for a long time.

This type of reactor has been built, small scale, and is usually referred to as a slow breeder reactor. These types of reactor run too hot for water to be used effectively as a coolant. They have to use something else.

Some use Helium or CO2 gas, some use liquid sodium or some molten salt. Each of these is much harder to work with than simple water is.

I believe that this proposal would use Liquid Sodium as a coolant. Hot sodium burns quite fiercely if exposed to air. Just something to think about. Clinch River did a lot of work on sodium cooled reactors in the late 1970's. The French also have around 40 years of experience using a sodium cooled reactor. Perhaps we should talk to them.

The Traveling Wave Reactor is a slow breeder reactor. So far though, it's just a paper proposal.

1166 Days Ago

12/23/2011

READ THE ARTICLE! USE MOLTEN LEAD AS THE COOLANT.

2197 Days Ago

02/25/2009

Technology will happen

This technology will be developed and used by other countries that have stockpiles of spent fuel, experience with nuclear technology, and climates less hospitable to solar and wind.

The containment and safety (coolant system failure means what?) are two issues that require some focus internationally. Is this reaction relatively controllable and can it be quenched easily and quickly?

This process degrades spent fuel that may be reprocessed into weapons. Reprocessing is a security and environmental threat far in excess of this alternative.

What are the potentially smallest configurations of this reactor style?

2167 Days Ago

03/27/2009

The fact is: The scale of the energy problem is so large that we will need to employ all viable non-carbon sources to get off of carbon based fuels.

The traveling wave reactor has many possible advantages of less maintenance and lower proliferation potential than breeder or traditional reactors. It should be a high priority for development IMHO.

2196 Days Ago

02/26/2009

Other good designs

Other designs that have traction are the Fast Reactor type, http://www.nextgenerationnuclearplant.com/index.shtml

http://nuclear.inl.gov/gen4/index.shtml

How they burn without proliferation material!

http://www.world-nuclear.org/info/inf98.html

I think these designs address proliferation and waste much better than the design outlined here.

They area also more inherently safe, since they have no critical fuel they can’t go super critical.

2195 Days Ago

02/27/2009

sstar

How is this different than the sstar reactor, proposed by Lawrence Livermore some years ago?

2164 Days Ago

03/30/2009

I think riffcon is correct, Intellectual Venture's own American Nuclear Society published paper cites the Teller, Ishikawa, and Wood paper from 1995 (although they cite the 2003 version not the original 1995), available at:

http://www.osti.gov/bridge/product.biblio.jsp?osti_id=231377

When the article states "the traveling-wave reactor is noteworthy for having come from something that barely exists in the nuclear industry: a privately funded research company". I don't see how this is true, the travelling wave reactor really came from national labs, just as every type of nuclear reactor I can think of (PWR, BWR, SFR, gas cooled, etc)has begun and tested in some form at a national lab.

2191 Days Ago

03/03/2009

Nuclear Deflagration Wave

From the video, it looks like the burn progression of a cigarette. What exactly is a nuclear deflagration wave? When I think of deflagration, I think of combustion. I'm not sure I can visualize what nuclear deflagration is.

2190 Days Ago

03/04/2009

Sanman:

Think of it as a probability calculation of fission via predictible statistics of thermalization of neutrons into the power source. Normally, in an evenly distributed nuclear fuel arrangement, the fissible material dead-center on a 2-dimensional plane has the highest probability of reactive interaction and fission (due to fewer non-reactive escape vectors), which goes up at a higher than linear rate as the reaction travels in a 3-dimensional style (basically, if you pack the core evenly, the middle will burn out a lot faster than the edges).

To offset this 'quick burn' for the reactive material in an uneven fashion, so to speak, careful calculations are made to determine how dense the fissible material will be distributed to provide for an even probabilistic consumption rate. All that wave is, is a desired form and rate of fuel consumption based on how they place the fuel. And the deflagration is just how quickly and in what manner the fuel is consumed, much like how quickly the burning material is consumed in a fire.

2188 Days Ago

03/06/2009

In the initial design of the traveling wave reactor (http://physci.llnl.gov/adv_energy_src/figure4.html

Big changes, fewer details on technology: credibility damaged.

1166 Days Ago

12/23/2011

Sodium could be replaced with molten lead, problem solved.

2191 Days Ago

03/03/2009

safetey of traveling wave

Has anyone ever safely cooled a reactor by pumping liquid sodium at 600C? Has it ever been done without leaks or fires? What would be the consequence of a leak in a reactor that produces large amounts of plutonium? Don't any of you guys ever consider questions like these?

2190 Days Ago

03/04/2009

From TFA:

«Although there are still some basic design issues to be worked out--for instance, precise models of how the reactor would behave under accident conditions--Gilleland thinks a commercial unit could be running by the early 2020s.»

Seems they are already aware of some concerns about security. The nuclear industry is probably the most controlled industry in the world and for sure, there is a long serie of acceptance tests before any new design can be put into production. They still have 11 years of development before having a commercially viable product.

Yes; the US Navy had a safe, working prototype of a liquid sodium moderated reactor in operation as early as the late 60s. It's designs were used as the basis for a couple of Naval reactor styles (although ultimately it was deemed not cost effective, due to special corrosion preventions needed). It's very workable, and I believe there are a couple of foreign designes that use liquid sodium today.

"Has it ever been done without leaks or fires?" Numerous times. We've come a LONG way from the operator stupidity of Chernobyl and 3 Mile Island; please bear in mind that both of those were due to lack of understanding on the operator's behalf, and willful overriding of many, many redundant safety features, and could have never happened even then under normal operating conditions.

"What would be the consequence of a leak in a reactor that produces large amounts of plutonium?"

Almost nil. Any radiative isotopes of sodium that we have knowledge of have half-lives measuring in the thousands of seconds, so moderated contamination is not a worry. Any out-of system contamination that could possibly happen (God forbid) could easily be caught with conventional salinity detectors set in a perimeter around the site.

"Don't any of you guys ever consider questions like these?" Sure they do. There have been a number of exciting advances within the industry; it's just that they get drowned out with cries of 'China Syndrome!' and 'Chernobyl!' and the like by misinformed or uninformed individuals. As for waste; well, if I remember my chains right, P239 ultimately ends up at U235, with a fair number of the byproducts ending up as useable products for things like industrial non-destructive testing and medical radiological therapy sources.

2190 Days Ago

03/04/2009

I suppose you have no worries about fast breeders either. The "heaven forbid" option is all too real if sometime in the 100 year lifetime of a traveling wave reactor--a sodium pump would fail. But that would never happen-- would it.

2189 Days Ago

03/05/2009

Tammons, you are an idiot.

Encase the reactor vessel in a few thousand tonnes of reinforced concrete (oh, it will be anyway) and nobody is going to get at it without a long, drawn out process.

As far as the sodium pump failing, what would happen is the same as in a liquid fluoride reactor: The freeze plug would melt, the core would dump out into non-critical storage vessels, and the reactor would shut itself down, gracefully. BTW, that all happens as the default, no power solution: It requires an active power source to keep things going.

The only long-lived byproduct of the Actinium series (which has U-235 in it) is Pa-231, an alpha emitter and as such not a particularly difficult issue to deal with (being blocked by a sheet of paper, cloth, skin, etc).

Since reading about nuclear energy obviously causes you to soil yourself, why not go read about Barney, the friendly dinosaur? He's more your speed.

2189 Days Ago

03/05/2009

so sure of yourself-- let's see who else you can convince.

2187 Days Ago

03/07/2009

He doesn't need to convince me, nor anybody else who has any idea about how things work in the real world. He's also right that you're either uninformed or misinformed or both. Seems like you are the one so sure of yourself that thousands of other people haven't actually thought out the most basic of questions. You must think yourself quite a genius and everyone else in the world quite ignorant. Before you open your mouth (or your fingers in this case), open your mind, make sure you understand what is actually happening, and then maybe ask some intelligent questions. You'll get a lot farther in life.

I, for one, see great promise in new designs such as this one. Due to the heavy regulation and government-mandated secrecy of this industry, innovative thought has been all but snuffed out in the field for many decades. I wish the team all the best with their reactor.

2185 Days Ago

03/09/2009

Well, as long as I only have to convince people who have at least a little knowledge on the subject, and critical reasoning abilities.

Too bad for you, I suppose.

BTW, industrial chemical processes go on every day of the year all around the globe where high-temp liquid sodium is pumped around. It's not rocket surgery.

But, live true to your warped ideas - starting by saving energy: Turn off your electrical mains and live without power. Note: That means you will have to live without renewable energy as well, since it's made with nasty old commercial power. No fires for cooking either (greenhouse gases). And better not breed, both as an improvement of the gene pool and to reduce mans footprint on mother gaia.

Oh, and if at all possible, please arrange your demise as quickly as possible (see gaia, above).

2188 Days Ago

03/06/2009

Re: safety of traveling wave

Yes of course. The Superphénix fast breeder reactor was connected to the French grid from 1986 to 1997, during which it produced 8,000 MWh. It was a prototype which suffered cost overruns and incidents in the beginning. Eventually it was decided to stop it for strictly political reasons. Ironically, the year it was stopped, it had achieved the best availability (90%) of all French nuclear reactors.

2159 Days Ago

04/04/2009

Interesting question, "has anyone done this before?" Would you believe, Rocketdyne built a sodium-cooled breeder reactor just north of Los Angleles? In fact, there was a partial core meltdown at that facility. Couldn't have been that bad, though, because you never hear the name Simi Valley thrown around when people talk about nuclear accidents, right?

Turns out, apparently most experts consider it to have been worse than Three Mile Island. Considerably. http://www.loe.org/shows/segments.htm?programid=06-p13-00003&segmentid=1

This was a 20MW research reactor, and yet it released 100 times the radioactive iodine that 3 Mile Island did.

Fact is, the hyperbole of a few vocal opponents of anything non-nuclear neatly ignores:

1) Nuclear plants are incredibly expensive, not just in terms of research, but construction costs. Not just the construction costs, but maintenance. Not just the maintenance, but decomissioning. Not just the decomissioning, but the cleanup. Then, what about the spent fuel? I challenge anyone to find a top-down nuclear powerplant proposal that includes anything beyond construction & basic maintenance cost.

2) Reactor support equipment still has a very short life when exposed to torrential, hard radiation. Sure, reduction of fueling interval to 100 years cuts down on a few costs. But not nearly a majority.

3) Solar panels aren't the only way to harness sunlight. Plants are better than 98% efficient at turning sunlight into chemical energy.

Why don't we spend a fraction of the money required for research & construction of a bevvy of nuclear plants of already demonstrably dangerous quality, and turn our efforts to researching new ways to harness sunlight? We've got a nice buffer zone between us and that particular reactor. To write solar energy off as unfeasible is incredibly short sighted (solar just hit 1USD/watt), and to impune the intelligence of others for explaining that is pretty tactless.

@tammons : your questions about the safety of using Liquid Sodium in a nuclear reactor are valid. One of the problems is very simple: Sodium reacts chemically with both air and water, and will burn strongly with either. Hence sodium leaks become a significant issue with sodium cooled reactors. The history of accidents is long, just some were:- the Sodium Reactor experiment at Santa Susana Field Laboratory" (1957 - 1964, the first commercial power plant in the world to experience a core meltdown)- Fermi 1 fast breeder reactor meltdown (1966)- the Japanese Monju sodium cooled fast reactor, which suffered in 1995 a sodium fire (fortunately, in a secondary sodium coolant system, where sodium was not radioactive). This led to an very long repair work over years (not to mention an astonishing chain of suicides across the management of the plant after a cover up was discovered). In short, the reactor (which cost 25 billion $) produced 1 hour of electricity (in 20+ years!), before being abandoned (for another accident, not related to sodium) in 2012.There are other forms of nuclear power, that are far safer. Look for the Molten Salt Reactor (MSR), now called in the US the Liquid Fluoride Thorium Reactor (LFTR). First developed in the 60s (by Alvin Weinberg at the Oak Ridge National Lab), it was abandoned in 1973 when Nixon decided to pursue the "Plutonium Fast Breeder". Now, China (of course) is working on it (since 2011) having placed 400 scientists and engineers on the project. In US, there is an engineer, Kirk Sorensen, who leads a campaign for the LFTR (see in facebook energyfromthorium). (I translate LFTR/MSR videos in 4 languages in: youtube.com/raulparolari ).

2191 Days Ago

03/03/2009

Unsupervised nuclear reactors

They are bound to have problems. No system like that is fool proof. The waste products can be used in dirty bombs or processed into real nuclear weapons. Leaks in the containment vessel can pollute aquifers and make a lot of real estate

uninhabitable. Solar is the way to go.

2190 Days Ago

03/04/2009

Where can I buy one?

This thing sound incredible, fuel it once and it burns for a 100+ years? Now this is some real Star Trek stuff. We could build a farm of these underground in a salt mine or in the desert and not have to worry about refueling them for 100+ years. I am all for green power, especially the kind that http://thumbnails.hulu.com/10/371/35488_384x288_generated__b3j9geceh0goksvqii6ajg.jpg

2185 Days Ago

03/09/2009

I guess you dont care that if your backyard reactor was cracked it might leak into the yard kill you and pollute everyone's drinking water if you live over an aquifer like I do.

2188 Days Ago

03/06/2009

Love it, now what do the politicians say?

I think this is a great design, and obviously serious consideration will be given to it to improve it further and address concerns.

But My Question is,

"what will the politicians think about it?" Politics is something I am not really good at, but I am guessing based on the past history of the US, there will be much difficulty selling it, especially to states with large coal lobbies, and hydro-electric.

What do you think?

Brian Glassman

Technology

Commercialization

Innovation Management

2185 Days Ago

03/09/2009

Well, first we would have to determine "Do politicians think".

That could take a while....

2187 Days Ago

03/07/2009

why 2020

Hi,

might be a naive question but why does it take so long to commercialize? Can't this be sped up?

2187 Days Ago

03/07/2009

It takes a series of steps to commercialize a new reactor design - tests on plant components and fuel, demonstration plant, prototype plant, commercial plant. Each step can take 5-10 years for design, licensing, construction, operation, and verification. 2020, even 2030, for a commercial plant is optimistic.

2187 Days Ago

03/07/2009

This lightly touches on the real reason it takes so long to do this stuff. The main delay is moving the paperwork from one bureaucrat's desk to the next, where that one has to decide if approving something new will delay the next raise or promotion. I am amazed this is being done in this country, since several other nations have a much more sensible attitude about nuclear power. In 1972 I did a problem set for 3.11, designing a containment vessel for a fusion reactor. I'm coming up on my 35th reunion, where are my fusion reactors???

2185 Days Ago

03/09/2009

why cut the brakes on the regulatory process?

2187 Days Ago

03/07/2009

Go for it

We've got a hell of a lot of scaling to do to get off of fossil fuels. Nuclear has got to be pushed as does solar etc.

On the other hand -- I want one of these for my house. The design is smart -- probably great for outer space use too -- Mars etc.

I know there are designs for "nuclear batteries" that would power a small city for say 5 years. Could a scaled down version of this do the same, but for 30-40 years?

2186 Days Ago

03/08/2009

I get a real kick out of the nonsense coming from the current administration about all the green initiatives that will replace those nasty coal plants. Yes, Obama will double the amount of renewable power in a decade. He will take us from 1% of the capacity of the grid to 2%. Or if you are generous, maybe 3%. Whoopie. This reactor represents a real breakthrough in concept, and should be pushed. Of course, looking at some of the comments shows the usual problems will abound: twits that know nothing about the science or engineering involved will still create strawman demons to scare us into not using the one power source that fits all the greenies' needs. Protn7, you obviously have never seen how a nuclear reactor is constructed. The housing structure is several FEET thick of heavily reinforced concrete, designed to take a direct hit by a large missle, and the reactor is housed in a steel containment vessel designed to take whatever could get through all that concrete. A 911-type strike would not breach a current-design nuke. With that level of containment, how the heck do you expect to contaminate the aquifers? Not to mention, a lot of those aquifers are contaminated anyway, at least in places like Niger or Colorado. Where do you think uranium comes from, the uranium fairy? A nuke that burns it's own garbage to make more power and emits no carbon should be the answer to a maiden's prayer.

2185 Days Ago

03/09/2009

And in the mean time, after telling us we can't set our thermostats at 72F he cranks the WH up to orchid growing levels.....

2184 Days Ago

03/10/2009

Sodium and water

Since water is the choice for running turbines and sodium reacts violently with water, a heat exchanger leak seems catastrophic. Sodium is required for nuclear properties. However, if the sodium heated another liquid (not sure what would be a good choice) which then heated water a single leak wouldn't cause sodium to come into contact with water.

2179 Days Ago

03/15/2009

I don't know that I would call a leak "catastrophic" but you would certainly have to account for the possibility. If the half life of irradiated sodium is short enough, then a secondary non-reactive exchange medium (e.g. lead) could certainly be used.

1181 Days Ago

12/08/2011

Oil is generally used as the secondary heat loop system. If properly chosen, it doesn't react chemically with either end. It does need to be changed periodically, as it tends to thicken.

2170 Days Ago

03/24/2009

debate?

I am amazed at how unpleasant some of the comments in this discussion are. They make the authors sound like petulant school children and/or bullies. Would you be this uncivil to someone in person?

Oh, and with regards to the comment:

"We've come a LONG way from the operator stupidity of Chernobyl and 3 Mile Island; please bear in mind that both of those were due to lack of understanding on the operator's behalf, and willful overriding of many, many redundant safety features, and could have never happened even then under normal operating conditions."

How does that perspective compare to the accepted consensus that the Three Mile Island accident was due to inadequate training and ambiguous control room indicators (i.e human factors engineering).

Saying that it "could have never happened even then under normal operating conditions" is fatuous.

1905 Days Ago

12/14/2009

Traveling-Wave Reactor

hi

my question is about the core of this new type of reactor:

first of all has any core been proposed for this type of reactor?

basically, is this type of reactor has a core like of currently plant cores? (made of several fuel assemblies)

could we transfer the spent Fuel assemblies from currently plants to the new TWR plant

1181 Days Ago

12/08/2011

No. Different geometries.

1648 Days Ago

08/28/2010

Materials

I wonder with the extraordinary life the the TWR how the structural materials will perform. If we are talking 50-100 years, the fluence will be so high that I would be concerned with structural integrity and neutron embrittlement.

1181 Days Ago

12/08/2011

Those are valid concerns. The brittleness problem is caused by transmutation of some of the alloy atoms of the steel (usually not iron, which is quite stable). But, those sorts of problems are addressed in the engineering phase.

This is still in the scientific/proposal stage. Engineering will come later. The next stage is actually regulatory, then financial. Only after all that can we get to the engineering.